An upper-level trough has brought unusually heavy rain to parts of the Pilbara in the last 24 hours, a time when rain is normally at a minimum.

Moisture has been streaming over parts of the Pilbara, thanks to the trough and warmer-than-normal waters off the coast of northwest WA. Around lunchtime on Saturday, the odd shower started turning heavier, and to 9am Sunday some places had collected over 50mm of rain.

 Image: cloud and rain streaming over parts of the Pilbara on Saturday evening.

Between about 1pm Saturday and 3am Sunday, Roebourne Airport recorded 58.6mm. The average for the entire month of July is just over 10mm. By 5am Sunday, Karratha had received 56mm. Karratha’s July average rain is just under 15mm. For both places, it was the highest July day's rain in 15 years.

Rain totals became a lot more modest further inland, however Barimunya managed to receive over 17mm. Showers over Port Hedland on Sunday morning were too light to record anything in the airport gauge.

The trough is weakening and showers are drying up, returning to what is normal for this time of year in the Pilbara.